In particular, the present invention is particularly useful in the field of excavating machines for making piles for foundations.
The technology for making piles of large diameter for foundations provides three main excavation methods, corresponding to three different excavating set-ups or configurations of the excavating machine.
The first method is LDP (large diameter pile) or drilled pile with telescopic Kelly rod or Kelly rod to which a tool of the bucket or drill type can be applied.
The second method is CFA (continuous flight auger) or perforated pile with continuous propeller provided or not with an extension sleeve.
The third method is CSP (cased secant pile) or perforated pile with cased propeller that provides excavating by moving both a continuous propeller and a casing pipe inside which the aforementioned propeller can slide.
All of the aforementioned methods provide an installation on a self-propelled excavating machine, preferably tracked and equipped with a substantially vertical guide tower equipped with suitable guides, on which rotating tables slide, adapted for generating the motion of rods, propellers and/or pipes. Different types of actuators (cable winches and/or cylinders and/or gearmotors) mounted on the machine ensure the sliding of said rotating tables along the guides of the tower (with a substantially vertical movement), so as to be able to apply downward fixing forces or upward extraction forces to said excavating means.
The three methods require machines fitted out in a very different way. The conversion of a machine to pass from one method to another is currently very onerous both in terms of time and in terms of costs for the investment in different equipment that it is necessary to replace to pass from one set-up to the other.
The method of LDP pile, thanks to the telescopic structure of the Kelly rod, can make excavations up to great depths (even up to 100 m and more) and can require the use of mud made with water and bentonite or polymers to support the walls of the excavation, because the excavation remains open for a long time (many filling cycles of the bucket are needs, and therefore it is certainly slower with respect to the excavation according to the method of CFA pile which, indeed, makes the excavation in a single stroke of the tool), because the transit repeated many times of the excavating means (bucket, drills, core drills, and so on) tends to make the walls collapse, and particularly because there are no mechanical means that support the walls of the hole. At the end of excavation, the jet of concrete to make the pile is carried out through pipes that are lowered into the excavation and that allow the concrete to be pumped from the bottom of the excavation. As the level of concrete progressively increases inside the excavation, the mud is sucked in.
As an alternative to filling the excavation through mud to ensure that the walls are supported, the hole can be supported through a coating and excavation pipe (casing) that is fixed directly by the rotating table of the excavating machine or can be fixed by an oscillating clamp or by a so-called full-rotator. In the case in which a full-rotator is used, it is arranged at the centre of the hole, generally connected to the truck of the excavating machine or even separate and hydraulically independent. The oscillating clamp or the full-rotator, through alternate oscillations or continuous movements, fix the pipe to obtain a protection of the hole for a partial or total segment of the excavation depth. If the required protection is partial and extends for a few meters or tens of meters, the insertion of the casing in the ground can be done directly with the rotating table of the excavating machine; otherwise, if the protection of the casing is required for greater depths an oscillating clamp or a full-rotator is necessary.
With reference in particular to FIG. 1A, an excavating machine of the LDP type for making piles with set-up and technology of the LDP type is shown. A supporting machine body or tower or carrier 1 that is generally tracked is equipped with a single rotating table or rotary for Kelly rods 2 that is moved in translation along a guide tower 3 that is vertical or slightly inclined on the vertical through various types of actuators like for example cable winches 6 with return pulleys, or typically hydraulic cylinders connected with a terminal to the guide tower 3 and with another terminal to the rotating table for Kelly rods 2, or gearmotors typically using a chain where the terminals of the chain are constrained to the rotating table for Kelly rods 2. A Kelly rod generally with telescopic structure having many extensions 5 crosses the rotating table for Kelly rods 2 from which it receives torque and thrust through a system of abutment strips present both on the outer surface of the rod and on the inner surface of a pipe, also called wear sleeve, present in the rotary for Kelly rods 2. In the constructive solution shown in FIG. 1A, the rotary for Kelly rods 2 is moved along the guide tower 3 through a winch 6 positioned on the tower itself, called pulling-pushing winch. The special feature of the pulling-pushing winch 6 is that of having two cables or two independent branches of a same cable on the same drum, coming out from the drum in opposite directions. One of the cables is directed towards the upper part of the tower and the other is directed towards the lower part of the tower, and through the different return sheaves present on the guide tower 3 they are both connected to the rotating table for Kelly rods 2. Preferably, one of the cables is fixed to the upper part of the rotary for Kelly rods 2 and the other is fixed to the lower part of the rotary for Kelly rods 2. In this way, when the upper cable is placed under traction by the rotation of the winch it provides the lifting or extraction pull to the rotary for Kelly rods 2 whereas when the lower cable is placed under traction by the rotation of the winch it provides the fixing thrust to the rotary 2. Since they are wound on the same drum, while one cable winds up the other unwinds and vice-versa. The pull of the pulling-pushing winch 6 on the rotary for Kelly rods 2 can be direct or transmitted to multiply the pull actually acting on the rotary for Kelly rods 2 (for example a double-tackle pull is common).
The telescopic Kelly rod 5 is, on the other hand, made to lift or release by a further manoeuvring cable 7 connected to the rod itself and that is transmitted by a head of the LDP type 4 and actuated by a further manoeuvring winch not visible in FIG. 1A since it is generally positioned in the machine body or tower 1.
However, in some possible variant embodiments such a further manoeuvring winch could be mounted on the guide tower 3. The translation movement of the rotating table for Kelly rods 2 is therefore independent from that of the rod 5 because the table of the LDP type 2 and the rod 5 are actuated by two different actuators and therefore a mutual sliding is also possible when their strips are not engaged with each other.
The telescopic Kelly rod 5 is equipped in its lower part with an attachment to be able to fix an excavation tool of the bucket (cup) or propeller drill type 8.
The rotary for Kelly rods 2 can have a structure made up according to different embodiments. In a first embodiment the rotary for Kelly rods 2 can have a monolithic bearing frame that comprises both the guide means (pads, and seats) for coupling with the guides of the tower and the return sheaves of the cables of the pulling-pushing winch 6. In a second embodiment the rotary for Kelly rods 2 can comprise a trolley that is separable from the bearing frame of the rotary for Kelly rods 2 through pin or peg systems. In this case, the trolley is equipped both with guide means (pads and seats) to couple with the guides of the tower 3 and with the return sheaves. In this case, the actuators of the pulling-pushing winch 6, i.e. the cables of the winch or the hydraulic cylinder, fix to the trolley. In a further variant, between the trolley and the bearing frame it is possible to insert a spacer than increases the distance between the axis of the pipe of the rotary and the surface of the guides. This distance is generally called “centre to centre drilling distance”.
The possibility of inserting or removing the spacer thus allows to modify the centre to centre drilling distance to better adapt it to the different excavation technologies.
In any case, the rotary for Kelly rods 2 comprises a monolithic structure or frame, a dragging sleeve rotatably connected to the monolithic structure through a fifth wheel or bearings made up of an inner ring and an outer ring, a ring gear integral with the dragging sleeve, one or more motors arranged to engage with such a ring gear and arranged to carry out such a dragging sleeve in rotation, and a wear sleeve arranged to couple both with the dragging sleeve, and with a Kelly rod to transmit the rotation motion to such a Kelly rod.
In the design of the rotaries for Kelly rods, the sizing is usually carried out starting from the establishing the maximum diameter of the telescopic Kelly rod intended to be installed on a certain excavating machine. From such a value, a wear sleeve is provided that has the minimum inner diameter sufficient to house the telescopic Kelly rod and that has the smallest possible thickness to limit the required dimensions of the fifth wheel or of the bearings of the rotary. In the same way, a dragging sleeve is provided that has an inner diameter sufficient to house the wear sleeve and that has the smallest possible thickness to limit the required dimensions of the fifth wheel or of the bearings. Finally, the fifth wheel or the bearings are selected of the smallest possible size that have a passage diameter of the inner ring sufficient to house the dragging sleeve, and which have the remaining dimensions compatible with supporting the loads that will develop in the operative excavation steps. As a result of this, the difference between the inner diameter of the dragging sleeve and the outer diameter of the telescopic Kelly rod is minimal, for example a few tens of millimeters. This selection is made mainly to keep down the space occupied by the rotary and to keep down the weight of the fifth wheel or of the bearings.
The method of CFA pile, which provides for the use of the continuous excavating propeller, is used to make excavations of medium/low depth, in general up to 40 m. Drilling is carried out dry since the support of the walls of the excavation is left to the outer edge of the spire of the propeller. In order to increase the maximum depth of the pile without increasing the height of the guide tower, the so-called extension sleeve or “Kelly sleeve” is used. This accessory is an extension arranged in the upper part of the propeller, for a length of 6-8 m that is in the form of a pipe having diameter substantially equal to that of the core of the propeller, externally equipped with strips for the entire length thereof and with bayonet couplings (mechanical abutment) at the upper and lower ends, in which the dragging sleeve of the rotating table abuts. Such an accessory is mounted above the continuous excavating propeller so as to result as passing through the rotating table, and allows an increase in excavation depth equal to its length. Differently from propellers, the extension sleeve does not have spires and this causes some problems in the drilling of incoherent grounds like for example the collapsing of the walls in the excavation part without spires, and the difficulty in lifting the waste materials.
FIG. 1B shows an excavating machine of the CFA type to make piles with set-up and technology of the CFA type, in which the CFA set-up is obtained starting from the LDP version described earlier. Indeed, details and elements that are similar—or having an analogous function—to those of the drilling machine for LDP technology described earlier, are associated with the same alphanumeric references.
A supporting machine body or tower or carrier 1 that is generally tracked moves a rotating table or rotary for propellers 2b along a substantially vertical guide tower 3. A continuous excavating propeller 9 that is almost as long as the guide tower 3 is positioned below the rotating table for propellers 2b and fixed to the latter, from which it receives torque and thrust. The rotating table for propellers 2b can be moved along the tower in various ways: in a first way the rotating table for propellers 2b is moved using only the pulling-pushing winch 6 already described for the LDP set-up; otherwise, in a second way it is possible to carry out a “combined pull” by also applying to the rotary for propellers 2b the pull generated by an additional manoeuvring winch arranged in the supporting machine body (or possibly on the guide tower 3) that is connected to the upper part of the rotary for propellers 2b through the further manoeuvring cable 7.
The rotary for propellers 2b can be equipped with sheaves positioned in its upper part to transmit the further cable 7 and make a tackle pull (for example a double-tackle pull). Through the further cable 7 it is thus possible to apply only a pull to the rotary for propellers 2b but not a thrust. The pulling-pushing winch 6, on the other hand, can provide both a thrust and a pull to the rotating table for propellers 2b. When a “combined pull” is carried out on the propeller both the pulling-pushing winch 6 and the additional winch that commands the further cable 7 are actuated simultaneously, so as to combine their actions and obtain a sum of the pulls. A lower guide 10 fixed on the guide tower 3 and generally openable, ensures the verticality of the advancing continuous excavating propeller 9. An extension sleeve 11 with strips, equipped with two couplings at the ends, allows to increase the depth of the pile to values greater than the length of the continuous excavating propeller 9. The guide tower 3 is equipped with a head of the CFA type 4b suitable for CFA that could differ from the head of the LDP type 4 suitable for LDP because it could require mounting a return pulley in a more withdrawn position, in order to create sufficient space for the passage of the extension sleeve 11, or it could require that a different inclination is taken up so as to allow the extension sleeve 11 to pass. The rotating table for propellers 2b differs slightly from the rotating table for Kelly rods 2 due to the presence of a diameter adapter sleeve that is inserted in the rotating table for propellers 2b and that allows this extension sleeve 11 to be used to connect to the continuous excavating propeller 9.
The method of CSP pile is used mainly to carry out mutually adjacent or secant piles. When it is wished to carry out a sequence of piles, all intersecting, so as to form a sort of diaphragm or partition in the ground, this CSP technology is adopted carrying out a suitable process. The process provides that firstly a series of holes are carried out, called primary holes placed aligned at a certain distance to each other, and that thereafter a second series of holes are carried out, called secondary holes that are arranged in the interspaces between the primary holes already made, and intersect them for small portions. Of course, the holes for the secondary piles are carried out when the primary piles have already solidified, therefore the propeller as well as the ground must also excavate the cement of the portion of the volume of the primary piles that is intersected by the secondary piles.
Precisely for this reason, the secondary piles tend to deviate their path from the area with hardened concrete towards those with ground or soft concrete, jeopardising the rectilinear nature of the diaphragm and the intersection with the primary piles, i.e. the continuity of the diaphragm. It is for this reason that the coating and excavating pipe or casing is used, which ensures the rectilinear nature of the pile: indeed, the pipe cuts the concrete of the primary piles, and the continuous excavating propeller, which is kept a few centimeters back with respect to the pipe, excavates the ground and lifts the debris.
Sometimes, on the other hand, it is advantageous to keep the continuous excavating propeller in an advanced position projecting with respect to the casing and excavating pipe to load the incoherent material; also in this case the pipe conserves its guide function to prevent the continuous excavating propeller from tending to flex given its low rigidity. The CSP technology provides the use of a rotating table for propellers adapted for moving the continuous propeller and a rotating table for pipes arranged on the same guides of the tower below the rotating table for propellers and coaxial to it. This rotating table for pipes is equipped with lifting or lowering means that are independent with respect to the rotating table for propellers and drags in translation and in rotation a casing and excavating pipe having diameter such as to contain the continuous excavating propeller. The rotary for pipes must also have an inner passage such as to allow the crossing of the propeller. The rotary for pipes, commonly called “intubator”, imparts a rotation to the casing and excavating pipe, preferably in the reverse direction to that of the continuous excavating propeller, and a thrust downwards. The continuous excavating propeller thus excavates a hole the walls of which are supported by the casing and excavating pipe.
The technology of CSP pile in the field of construction is also called CFA cased pile technology.
Moreover, there are applications known in the field of foundations for which the linear movement systems of the rotaries along the guide tower are not independent from one another like those of the type described up to now. There are variants in which one of the two rotaries is connected to a first movement system, for example a winch with direct or transmitted cables, whereas the other rotary, generally the rotary of the propeller, is equipped with a second movement system through linear actuators, generally hydraulic cylinders, which, when actuated, move one rotary with respect to the other and consequently move the continuous excavating propeller linearly with respect to the casing and excavating pipe. Generally, this movement is limited to an excursion that varies between 200 and 600 mm and allows a simpler but much more restrictive set-up during the excavation steps. One of the limitations of this solution is for example the fact that it is impossible to completely extract the continuous excavating propeller before the casing and excavating pipe is extracted. In this last constructive solution, the two rotaries can be mounted on the same trolley, in any case being able to have relative sliding, or they can be mounted on two independent trolleys. Again, in this solution, the movement system of the rotary that uses a winch preferably exploits a winch having a double branch to carry out both the extraction pulling through the upper branch and the fixing thrust through the lower branch.
In a further known variant, described in EP2048321B1, the encased propeller drilling system is made through a single rotary mechanically connected to a torque or revolution multiplier which in turn moves both the propeller and the pipe in rotation. The multiplier receives in input the torque and the rotation provided by the rotary and has the possibility of providing in output a rotation of the propeller in the clockwise direction and a simultaneous rotation of the pipe in the anti-clockwise direction.
With reference to FIG. 1C an excavating machine of the CSP type is illustrated with CSP set-up defined as standard. Details and elements that are similar—or having an analogous function—to those of the drilling machine for LDP or CFA technology described earlier, are associated with the same alphanumeric references. A generally tracked supporting machine body or tower or carrier 1 comprises a vertical guide tower 3 along which a rotating table or “rotary” for propellers 12 slides. A continuous excavating propeller 9 (not visible in this figure because hidden by the pipe) of slightly shorter length than that of the guide tower 3 is fixed to the rotating table for propellers 12, from which it receives torque and pulling or pushing forces to generate the sliding with respect to the tower 3.
The rotating table for propellers 12 is moved along the tower by a first manoeuvring winch not visible from the images because it is positioned in the machine body or tower. It is nevertheless possible to see the cable 7 coming out from such a winch, which is then transmitted in a head of the CSP type 16 arranged at the upper end of the guide tower 3. In the case in which through the cable 7 it is wished to carry out a multiple tackle pull applied to the rotary for propellers 12, suitable transmission means such as pulleys and blocks can be installed integrally to the rotating table for propellers 12. As movement means of the rotary for propellers 12 it is in any case possible to use actuators equivalent to the winch with cable, for example a motor equipped with a pinion that acts on a chain connected to the rotary. An extension sleeve 11 equipped with strips and with two attachments at the ends increases with its length the maximum executable depth of the pile. A rotating table or “rotary” for pipes of the CSP type 13 arranged under the rotary for propellers 12 is moved by a second pulling winch 14 and slides on the same guide tower 3 in a preferably independent manner from the rotary for propellers 12, thanks to the action of separate pulling and pushing means. The rotary for pipes of the CSP type 13 commonly called “intubator” is characterised by a large inner passage capable of housing the diameter of propeller 9 fixed under the rotary for propellers 12. This characteristic of allowing the crossing of the propeller, essential for the operation of CSP technology implies for the intubator 13 a considerable space and weight. A coating and excavation pipe or casing 15 sized to be able to contain the bulk of the continuous excavating propeller 9 is fixed under the intubator 13 from which it receives torque and thrust.
Such a casing and excavating pipe 15 is equipped with excavating teeth in its lower part and excavates a “core” in the ground that is immediately broken up by the coating and excavation propeller 9 kept slightly back with respect to the lower edge of the pipe 15. A lower guide 10 equipped with a passage coaxial to the axis of the rotaries 12 and 13 and fixed on the guide tower 3 that is generally openable ensures the verticality of the pipe in the first excavation steps keeping the lower part of the pipe aligned with the excavation axis.
The intubator 13 is created to work with rotation speed of a few revs per minute (maximum 5-10 rpm) and with a lot of torque, precisely because it drags pipes of great diameter that thus have a lot of friction surface with the ground. The torque curve of an intubator developed as a function of the rotation speed can be considered substantially flat; this means that the intubator provides the maximum torque both at the minimum rotation speed and at the maximum rotation speed. In the construction of intubators preference is given to the use of toothed fifth wheels of large dimensions, since the high circumference allows to arrange many teeth that couple with the pinions of the motors and allow to obtain high reduction ratios that make it possible to increase the torque produced. Given the low rotation speed a greasing of the gears is sufficient, which can be installed in a housing that is open at the bottom to allow greasing.
Otherwise, the rotary for the movement of Kelly rods or of continuous propeller, like the rotary for propellers 12, is created to have a more extensive and variable torque curve along the axis of the graph that expresses the rotation speed, i.e. a wider working range. In particular, the rotary for propellers or Kelly can work at low revolutions developing high torques (therefore a first segment of the torque graph will be flat) and then it can progressively increase the rotation speed at the expense of a reduction of torque developed (therefore the torque graph will progress like a descending parabola) until a high speed (for example up to 30-40 rpm) and low torque work condition is reached.
Therefore, the torque curve of a rotary for propellers or for rods could incorporate the torque curve of an intubator (for the same maximum torque able to be delivered) but not vice-versa, since the intubator can only reach a limited number of revs per minute.
This means that a rotary for propellers or Kelly rods could be made to work at the low rotation speeds typical of an intubator (5-10 rpm) with high torque, whereas an intubator cannot be made to work at high rotation speeds typical of excavation with propeller or Kelly rod.
This variability of the possible work conditions of the rotary is obtained thanks to some technical provisions in the construction of the rotary itself, like for example the presence of variable displacement motors, and the possibility of having a mechanical gearbox to modify the gears as the required speed or torque varies. Given the high rotation speeds required, in the rotaries for the movement of Kelly rods or for propellers, the inner gears (pinions of the motors and ring gear of the fifth wheel) are made to work in an oil bath. For this reason, they are installed in a housing arranged to be filled with oil (called “rotary case”) and equipped with sealing gaskets, as well as doors for loading and emptying the lubricating oil. The rotaries for the movement of Kelly rods or for propellers, like the rotary for propellers 12, are equipped with a further motor having high rotation speed called spin-off motor that is actuated during particular steps of the excavation. When excavation is carried out using a drill connected to Kelly rods as the tool, once the drill has been filled with excavated ground it is necessary to extract it from the excavation and unload the debris. The unloading step takes place by engaging the spin-off motor and actuating it for a short period. The spin-off motor acts by quickly rotating the drill in the opposite direction to that of winding of its spires, with a rotation speed that can vary from 50 to 150 revs per minute based on the size of the tool and of the rotary.
In this way, the centrifugal force pushes the debris to come out from the spaces between the spires, emptying the drill and falling to the ground.
It is known that rotating tables for Kelly rods can be converted into rotation tables for propellers; such conversion takes place by mounting in the rotary for Kelly rods an adapter adapted for reducing the inner passage of the rotary for Kelly rods and adapting it to the diameters of the extension sleeves used for mounting the continuous propellers. This reduction of the passage is necessary since the telescopic Kelly rods currently on the market generally have an outer diameter comprised between 324 and 630 millimeters, and preferably comprised between 355 mm and 558 mm, whereas the extension sleeves connected to the upper end of the continuous propellers generally have an outer diameter comprised between 150 and 356 millimeters.
In the prior art, an excavating machine of the LDP type like the one shown in FIG. 1A can be transformed or converted in an excavating machine of the CFA type like the one shown in FIG. 1B by modifying the rotary for Kelly rods 2 as described above, i.e. through the insertion of an adapter in the rotary for Kelly rods 2 in order to obtain a rotary for propellers 2b suitable for dragging the propeller. Of course, for the transformation it is also necessary to dismount the telescopic Kelly rods 5 and replace them with a continuous excavating propeller 9 obtaining the set-up shown in FIG. 1B. The rotary for Kelly rods and the rotary for propellers have substantially the same weight and the same performance in terms of torque and revs; therefore, the rotary for Kelly rods is substantially the same as the rotary for propellers except for the diameter adapter. In particular, these rotaries are generally selected of the maximum possible size to maximise the excavation performance of the machine, and such a selection is based on the respect of the maximum installable weight on the guide tower without compromising the frontal stability and on the respect of the structural resistance to torsion and flexing of the guide tower. Indeed, the rotary is positioned canti-levered with respect to the support surface provided by the tracks, and in a raised position with respect to the supporting machine body that can also reach the upper end of the guide tower; therefore, a rotary of excessive weight and size could cause the machine to tip over at the front or in any case insufficient stability for safety purposes.
If, starting from an excavating machine of the LDP type like the one shown in FIG. 1A, it is wished to modify its set-up to transform it into a standard excavating machine of the CSP standard type shown in FIG. 1C, it would not be possible to continue to use the rotary for Kelly rods 2 to move the continuous propeller for the CSP set-up, but it should be replaced with a rotary for propellers 12 of lesser size and weight. This replacement becomes necessary in known (standard) machines precisely so as not to compromise stability.
The standard method for the set-up in CSP version requires the addition of a known intubator 13 that as stated is heavier than the rotary for Kelly rods 2. In order to compensate for this increase in weight, generally the rotary for Kelly rods of the LDP type 2 is dismounted and it is replaced with a smaller and lighter rotary for propellers 12 for the movement of the propeller, while the intubator 13 moves the pipe/casing.
The reversible conversion of a machine of the LDP type of FIG. 1A into a standard machine of the CSP type of FIG. 1C requires the provision of two rotating tables, a first table for Kelly rods of the LDP type 2 of greater size and weight, a second table for propellers 12 of lower size and weight and a third table for pipes or intubator 13. Such additional components generally have substantial costs.
It should also be specified that in the standard CSP set-up, in order to maximise the performances of the machine in terms of extraction force of the propeller, the head of the CSP type 16 is also generally very different both from the head of the LDP type 4 and from the head of the CFA type 4b used in the CFA set-up of FIG. 1B obtained starting from the LDP set-up. Indeed, the head of the CSP type 16 is equipped with a greater number of pulleys, arranged differently and suitable for multiplying the pull of the manoeuvring winch associated with the machine body and the manoeuvring cable 7 of which is visible. Said multiplication in practice performs a multiple pull (generally a fourth-tackle pull) through a suitable “turning of the cables” on the pulleys of the guide tower and of the rotary, so that for the same pull provided by the winch a multiplied force is obtained that acts by lifting on the rotary and therefore on the propeller.
As is clear, the transformation of the LDP type machine into a Standard CSP machine according to known methods is very onerous both in terms of cost and in terms of time necessary for the transformation given that the two machine set-ups are substantially different. Major replacements of mechanical parts are necessary, which require the dismounting and remounting of various components also with regard to the hydraulic systems relative to the actuation of the rotaries.
The conversion of the standard LDP type machine (FIG. 1A) into a standard CSP type machine (FIG. 1C) according to the method used up to now in the prior art provides the following modification steps of the set-up:
a. dismounting the LDP 4 type head arranged for the first tackle pull; this also requires disconnecting the cable 7 from the rotary for Kelly rods 2 and unwinding it (disengaging it) from the pulleys of the LDP 4 type head.
b. mounting the head of type CSP 16, which has a different geometry and is arranged for fourth-tackle pull; in such a step it is necessary to rewind the manoeuvring cable 7, with a different turn with respect to that which it did with the LDP 4 type head, on the pulleys of the CSP 16 type head and on the pulleys arranged in the upper part of the rotary for Kelly rods 2.
c. dismounting the rotary for Kelly rods 2 from the guide tower 3 (and if it is equipped with a trolley it is also necessary to dismount the trolley) and undoing the cable turns that come from the pulling-pushing winch 6, i.e. disconnecting the cable from the rotary for Kelly rods 2 and unwinding it (disengaging it) from the pulleys of the rotary 2 or of its trolley.
d. mounting on the guide tower 3 the rotary for propellers 12 of smaller size, equipped in its upper part with blocks and pulleys suitable for fourth-tackle pull to be connected (engaged) to the manoeuvring cable 7 coming from the manoeuvring winch mounted on the tower.
e. installing pipes and systems for the new rotary for propellers 12, which is fed hydraulically or with another energy source.
f. mounting on the guide tower 3 the intubator 13 and the relative cleaning and debris-unloading means positioned over the intubator; in particular, in this step a cleaner (preferably using rollers) is mounted below the rotary for propellers 12.
g. installing the pipes and the systems for the intubator 13; such pipes are not the same ones used for the rotary for Kelly rods 2, since the intubator 13 requires different flow rates and oil pressures, and can have a different number of motors, as well as being able to have many actuators for additional functions with respect to the rotary.
h. dismounting the pulling-pushing winch 6 arranged for pulling-pushing with a cable that extends along two branches, an upper one and a lower one, and mounting the pulling winch 14 that can carry out only the pulling with a single cable that extends along a single upper branch.
i. connecting the cable of the pulling winch 14 to the trolley of the intubator 13 suitably making the “cable turns”.
As well as the steps listed above it is necessary to dismount the Kelly rods and install the continuous excavating propeller and the casing and excavating pipe and other steps of lesser relevance that will not be discussed further in the present description.
It should be emphasised that the replacement operations of the head are very long and complex. Indeed, in order to be able to move these heads weighing a few hundred kilos it is necessary to have an auxiliary crane.
Moreover, it is necessary to unscrew all of the bolted connections, dismount the head, position the new head and screw all of the connections back in.
It may therefore be the case that one same excavating machine, when set up according to LDP technology to be used with Kelly rods, mounts a rotary for Kelly rods 2 and when set up according to CSP technology mounts an additional intubator 13, of substantially greater size and weight than the rotary for Kelly rods 2, and a light upper rotary for propellers 12 replacing the rotary for Kelly rods 2. Therefore, in the prior art up to 3 rotating tables are necessary in order to be able to ensure the maximum technological flexibility, i.e. the possibility of modifying the set-ups, and the maximum performance, with clear worsening of costs.